Vehicle Ad-hoc Networks (VANETs) plays an essential role in enhancing safety, passenger services, and traffic management. VANETs often suffer from reliability issues and delays due to their dynamics. Multihoming, where vehicles communicate over multiple networks, is a possible approach to mitigate these problems. In this paper, we present a comprehensive survey exploring the integration of multihoming with Software-Defined Networking (SDN), Programming Protocol-independent Packet Processors (P4), and Service Function Chaining (SFC) in VANETs, a set of technologies that play an important role in modern vehicular networks. To select the papers to be analyzed in our survey, we used a four-stage process, starting with keyword searching and consisting of multiple filtering and a final grouping step. This process resulted in 300 research papers from 2009 to 2023. Our analysis revealed the importance of routing techniques tailored for dynamic VANET environments, highlighting the critical challenge of delays resulting from intermittent connectivity and rapid topology changes. To the best of our knowledge, available literature does not consider the integration of SDNs, P4, and SFC to improve connectivity in VANETs: some SDN applications include VANETs support but previous research tends to consider the use of P4 and SFC within data center contexts and security applications. Since P4 can simplify traffic management, SFC can help supporting services and policies, and technologies like Multi-Radio Access Technologies (M-RAT) can enable multihoming, the possibility of using SDNs with these technologies to support multihoming in VANET lays the foundation for future progress in vehicular communication systems. This approach shows potential for new developments and challenges, taking into account future trends and directions.